1. Field of the Invention
The present invention relates to handling and lifting attachments for boom-type vehicles and more particularly to an attachment which is particularly adaptable for use with a panel assembly of the type having a purline and a panel, the purline securely attached to the panel and disposed at an angle thereto.
2. Description of the Related Art
Modern techniques for constructing tilt-up type buildings involves installing spaced, vertical columns. Roof panel assemblies are also generally constructed (or at least stored) at one location at the construction site and must be transported via a boom-type vehicle through the columns to their desired point of installation. Referring to FIG. 5 of the drawings, which illustrates the environment in which the present invention operates, it can be readily seen how a navigational dilemma exists while transporting panel assemblies.
In this figure, the construction site is designated generally as 10. The vertical spaced columns 12 provide difficult obstacles for the boom-type vehicle 14 carrying a load as it navigates from the panel assembly storage area (not shown) at one area of the construction site to the area of installation shown in FIG. 5. It can be seen in this figure, as well as by reference to FIG. 2, that the typical roof panel assembly, designated generally as 16, includes a purline 18 attached to a panel 20. The panel 20 includes, typically, a relatively thin sheet of plywood 22 and a plurality of parallel spaced 2.times.4's, labeled 24. The panel assembly is typically about 50 feet wide. The panel assembly 16 typically further includes first metal clips 26 at the purline ends and second metal clips 28 at the ends of the members 24, as shown in FIG. 3.
Referring again to FIG. 5, the panel assembly 16 is transported to the point of installation, and the panel assembly 16 positioned so that the 2.times.4 clips 28 (not shown in this figure) fit over a purline 16 of a previously attached panel assembly 16 and the purline clips 26 engage structural beams 30, the panel assembly 16 then being securable in its position. The resulting roof structure is illustrated in FIG. 1.
Referring again to FIG. 5, it is noted that an attachment 32 to a boom 34, is illustrated. Attachment 32 is, in fact, the attachment of the present invention. (The discussion of this drawing, in this section of the patent application, should not be, by any means, construed as an acknowledgment that the attachment is prior art. Its inclusion in this section of the patent application has been made to assist the reader in attaining a better understanding of the environment in which the attachment operates and the problems faced by the present inventors in their endeavors.)
In a typical prior art forklift, a wooden cross member is fixedly attached to the fork tips to support the panel of the panel assembly. The heel portion of the fork supports the purline. The cross member typically has a height which is lower than the height of the purline and, as a result, the panel sits sloping downward and no adjustment can be made to hold it at a level attitude. When the panel assembly is reaching its point of installation, the ends of the 2.times.4's first come to rest on the existing purline. The forklift must than be lowered so that the presently installed purline comes to rest on the main structural beams. This presents compound navigational dilemmas and may even sacrifice the structural integrity of the panel assemblies. (The panel assemblies are generally quite flimsy and achieve a good portion of their structural integrity upon being connected to adjacent panels and structural beams.)
As can be seen by the environment illustrated in FIG. 5, maneuvering the tractor through the columns is very difficult. In prior art methods, the crane must be turned 180 degrees in order to pass between the columns. Furthermore, the panel assembly must be raised sufficiently to clear the panel above the structural beams. Navigation is very difficult without the ability of forward reach swing movements and fine adjustments thereof.
U.S. Pat. No. 4,280,785, entitled MULTI-DIRECTIONAL LIFTING AND HANDLING ATTACHMENT FOR A CRANE BOOM, issued to R. G. Albrecht, discloses a multi-directional lifting and handling device mounted on the end of a standard telescoping crane boom. The elongated generally fore and aft main frame of the device includes a hydraulic rotary actuator which selectively rotates a pivotally connected sub-frame about a transverse, substantially horizontal axis. A cradle-like framework, in turn, is rotatably connected to the sub-frame and is selectively rotated by a second hydraulic actuator, the cradle-like framework being rotatable about a longitudinal generally fore and aft axis. Work pieces, such as pipes, beams, or the like are detachably secured in the cradle-like framework by flexible chain straps which form a U-shaped clamp about the workpiece, the chain straps being easily attached to and detached from the load, facilitating quick loading and unloading of the object to be moved.
U.S. Pat. No. 4,553,899, entitled HIGH LIFT TRUCK WITH TELESCOPING BOOM ASSEMBLIES, issued to R. Magni, discloses a high lift truck with a first telescopic boom. Its essential feature, basically, is that of providing a second telescopic boom fixed immovably to the top end of the first raise-and-lower boom which is likewise telescopic, and hinges at the bottom with a mounting on the truck axis; the two booms thus associated, creating an obtuse angle such that the second boom will project forward along the line of the truck axis when the first boom is fully raised.
U.S. Pat. No. 4,382,743, entitled LOADING APPARATUS WITH A TILTABLE AND EXTENDABLE FORK CARRIAGE MOUNTED THEREON, issued to L. H. Newell discloses an apparatus including a mobile chassis having a turntable on which is supported a boom assembly. At the free end of the boom assembly, a forklift carriage is tiltably mounted which can be extended and retracted relative to the boom assembly.
U.S. Pat. No. 4,650,389, entitled MECHANISM AND METHOD FOR POSITIONING A FENDER ON A DOCK VERTICAL WALL, issued to P. J. Mulqueen, discloses a mechanism for positioning on a dock vertical wall a fender including spaced openings, the mechanism comprising a movable support, a first arm pivotally attached to the movable support, a first hydraulic cylinder piston rod assembly for pivoting the first arm, a second arm pivotally attached to the first arm, means for pivoting said second arm, a plurality of spaced projections attached to and extending from the second arm, and pins for releasably securing the projections in the spaced openings in the fender.
U.S. Pat. No. 4,082,197, entitled ARTICULATED HIGH LIFT VEHICLE, issued to R. N. Stedman discloses a vehicle comprising first and second frame assemblies pivotally connected together and actuating means, preferably extensible and retractable steering cylinders, interconnected between the frame assemblies to selectively pivot them relative to each other.
U S. Pat. No 4,583,907, entitled EXTENSIBLE APPARATUS, issued to R. J. Wimberley, discloses a flexible extensible apparatus for employing an end-use work tool for one of multiple purposes characterized by combinations of a pivotal base; main support structure; pivotally mounted support structure; extensible base unit having first and last respective pairs of booms and levers; attachments for the work tool; and a plurality of extension units each comprising respective pairs of booms and levers.
Thus, from the above recital of the problem to be faced and the above descriptions of references revealed in a patent search, it can be seen that prior art methods of attempting to solve the problems associated with present Applicant's endeavors is lacking. As will be disclosed below, the present invention provides an improved attachment for a boom-type vehicle which provides extremely versatile multi-directional lifting and handling capabilities. The present invention is particularly adaptable for use with a panel assembly of the type having a panel and a purline, the purline securely attached to the panel and disposed at an angle thereto.